OpenVPN TUN mode does not forward traffic through tunnel

[bimbar]

I just migrated from legacy to instances, and I used to have a TAP based tunnel routed via BGP.

server: 172.28.1.1, clients: 172.28.1.2 and 172.28.1.6

The configuration for that was client specific overrides for the clients, and a network of 172.28.1.0/28, of which the server automatically got the .1 .

So I migrated that 1:1, and the server interface would not get an IP, so that didn't work.

Switched to TUN, everything seemed fine, client can ping server, BGP session is active, but no traffic seems to be routed through the tunnel. TCPDUMP on the client says, packets are sent, TCPDUMP on the server, nothing except the unrouted traffic.

Then I switched to DCO just for the hell of it, and it works.

Any ideas? Could this be the dreaded openvpn builtin packet filter?

EDIT: On second thought, must have been the packet filter - but the question remains, why did the TAP interface not get an IP address?